This invention relates in general to form, fill, and seal packaging machinery of the type in which a continuous sheet of a packaging material is sequentially folded about a series of articles to be packaged, hot or cold sealed about the articles, and cut into individually sealed packages. More specifically, this invention pertains to a method and apparatus for testing the quality of crimped seals that are formed in overlapping portions of the sheet of the packaging material.
The formation of a plurality of individually sealed packages of articles using a single continuous sheet of a packaging material is well known in the art. A typical form, fill, and seal apparatus for accomplishing this is disclosed in U.S. Pat. Nos. 5,868,901 and 6,230,781, the disclosures of which are incorporated herein by reference. Briefly, however, a typical form, fill, and seal apparatus includes means for supporting a roll of a sheet of a packaging material, which is payed out and fed around various feed rollers to a folding shoe. The folding shoe continuously folds the longitudinal edges of the sheet of the packaging material about the sides of a plurality of articles which are moved longitudinally along a conveyor. The folded sheet of the packaging material is then moved along a support surface. As the folded longitudinal edges of the sheet are moved along the support surface, they are engaged by a pair of folding rollers disposed beneath the support surface. As a result, the longitudinal edges of the sheet of the packaging material are further folded downwardly in an overlapping manner. Then, a pair of grooved heat seal rollers disposed beneath the support surface engages the overlapping edges of the sheet of the packaging material so as to create a continuous longitudinal fin seal. The fin seal is next engaged by a pair of pull rollers, also disposed beneath the support surface, which advance the folded sheet of the packaging material (and the articles enclosed therein) through the apparatus. A deflector is provided in the support surface to fold the fin seal upwardly into flush engagement with the folded sheet of the packaging material.
A rotary crimping assembly is provided in the apparatus for laterally crimping and cutting the folded sheet of the packaging material so as to form a plurality of individually sealed packages. The crimping assembly includes an upper crimper bar that is disposed above the support surface for rotation about an axis extending generally perpendicular to the longitudinal movement of the sheet of the packaging material. A pair of upper crimpers are secured to opposite sides of the upper crimper bar for rotation therewith. Similarly, the crimping assembly includes a lower crimper bar that is disposed below the support surface for rotation about an axis extending generally perpendicular to the longitudinal movement of the sheet of the packaging material. A pair of lower crimpers are secured to opposite sides of the lower crimper bar for rotation therewith.
As the folded sheet of the packaging material is moved along the support surface, the upper and lower crimpers are rotated. As a result, leading edges of the upper and lower crimpers initially engage the folded sheet of the packaging material. When this occurs, the folded sheet of the packaging material is compressed between a downwardly facing crimping surface of the upper crimper and an upwardly facing crimping surface of the lower crimper. As a result, the overlapping layers that make up the folded sheet of the packaging material are sealed together to form a trailing edge seal for a packaged article. Further movement of the folded sheet of the packaging material and rotation of the upper and lower crimpers cause a cutting blade provided in one of the crimpers to be aligned with an anvil provided in the other of the crimpers. Consequently, the folded sheet of the packaging material is cut longitudinally into two pieces. Still further movement of the folded sheet of the packaging material and rotation of the upper and lower crimpers causes trailing edges of the upper and lower crimpers to engage the folded sheet of the packaging material. When this occurs, the folded sheet of the packaging material is compressed between a downwardly facing crimping surface of the upper crimper and an upwardly facing crimping surface of the lower crimper. As a result, the overlapping layers that make up the folded sheet of the packaging material are sealed together to form a leading edge seal for the next packaged article.
In some instances, the sheet of the packaging material is provided with a cohesive coating for accomplishing the seal when compressed. In other instances, an intermediate seal layer of a coating or other bonding material is provided. Also, it is sometimes desirable to heat the overlapping layers of the sheet of the packaging material when crimped to facilitate the sealing thereof. This can accomplished by heating the crimpers to an elevated temperature before compressing the layers of the packaging material therebetween.
As with most manufacturing processes, it is desirable to evaluate the quality of the crimping process in order to insure that the various overlapping layers of the packaging material will be reliably sealed when the above-described form, fill, and seal packaging machinery is operated. However, in the past, evaluations of this sort were made by operating the form, fill, and seal packaging machinery in the normal manner and removing some of the packaged articles for testing. This evaluation procedure is inefficient because the entire form, fill, and seal packaging machinery must be operated, and a number of packaged articles may have to be discarded if the seals are found to be not reliable. Thus, it would be desirable to provide a method and apparatus for testing the quality of crimped seals that are formed in overlapping portions of the sheet of the packaging material.